1. Field of the Invention
The present invention relates to a linear motion rolling guide unit that linearly guides a movable object to be moved, and which is equipped on, for example, a machine tool or industrial robot.
2. Description of the Prior Art
A typical example of this type of linear motion rolling guide unit of the prior art is shown in FIGS. 1 and 2.
As shown in the drawings, said-linear motion rolling guide unit has track rail 1, in which tracks in the form of track grooves la are formed in the right and left sides along the lengthwise direction, a slider in the form of sliding unit 3 able to move relative to track rail 1 and having rolling element circulating path 2 (the details of which will be described later), and a plurality of rolling elements in the form of balls 4 arranged and contained in said rolling element circulating path 2 which bear the load between track rail 1 and sliding unit 3 by circulating while rolling over said track grooves la accompanying movement of said sliding unit 3.
Sliding unit 3 has casing 6, provided so as to straddle track rail 1, a pair of end caps 7a and 7b coupled to the front and back ends of said casing 6, and two seals 8a and 8b attached to each of the outer surfaces of said end caps 7a and 6b. Furthermore, grease nipple 9 for supplying grease to the above-mentioned balls 4 is attached to end cap 7a. As shown in FIG. 2, rolling element circulating path 2 is composed of load bearing track groove 2a and return path 2b formed linearly and in parallel with each other in casing 6, and a pair of roughly semi-circular direction changing paths 2c and 2d formed in both end caps 7a and 7b that connect said load bearing track groove 2a and return path 2b at their ends. Furthermore, the above-mentioned load bearing track groove 2a corresponds to track groove 1a of track rail 1. In addition, in FIG. 1, reference numeral 11 indicates a retaining member that retains balls 4 so that they do not fall out of the above-mentioned load bearing track groove 2a.
A linear motion rolling guide unit having the above-mentioned constitution is arranged on, for example, the bed of a machine tool (not shown), and track rail 1 is fastened to said bed with bolts. A table for holding a workpiece and so on (not shown) is bolted to sliding unit 3, with this operating as the moving side. Namely, said table is reciprocated by a driving device not shown with a workpiece and so forth placed on said table. Furthermore, as shown in FIG. 1, a plurality of bolt insertion holes 1b for fastening to the above-mentioned bed and so on are formed in track rail 1. In addition, a plurality of threaded holes 6a are formed in the upper surface of casing 6 of sliding unit 3. The above-mentioned table is fastened to sliding unit 3 by bolts (not shown) that are screwed into these threaded holes 6a.
In the above-mentioned constitution, a clamping mechanism and so forth is provided for fastening said table to a stationary side in the form of a bed in order to completely stop the above-mentioned table at a certain position. However, depending on the apparatus on which a linear motion rolling guide unit is to be equipped, there are cases in which it is difficult to provide a clamping mechanism and so forth due to factors relating to structure, installation space and so on. In addition, even if such a clamping mechanism is provided, there is the additional disadvantage of forcing changes to be made in the designs of other mechanical components.